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Requirements on the manufacturer

EN ISO 1 561 3:2004, Specification and qualification of welding procedures for metallic materials —

Qualification based on pre-production welding test (ISO 15613:2004)

EN ISO 15614-1:2004 outlines the specifications and qualifications for welding procedures related to metallic materials, specifically focusing on the testing of welding procedures This standard covers arc and gas welding techniques for steels, as well as arc welding for nickel and nickel alloys, ensuring that welding practices meet established quality and safety criteria.

EN ISO 1 7663:2009, Welding — Quality requirements for heat treatment in connection with welding and allied processes (ISO 17663:2009)

CEN ISO/TR 1 5608:2005, Welding — Guidelines for a metallic materials grouping system (ISO/TR 15608:2005) "

!For the purposes of this document, the terms and definitions given in EN 1 3480-1 :201 2 together with the following apply

3.1 field run piping piping installed without preplanning by drawings of the piping routing and the support points

Note 1 to entry: Typical dimensions are DN 50 or smaller

3.2 spool (with or without overlength) prefabricated assembly of components which forms part of a piping system

3.3 cold forming forming at ambient temperature, but not below + 5 °C

3.4 hot forming for ferritic steels, forming at temperatures at or above the maximum permissible temperature for post-weld heat treatment; for austenitic and austenitic-ferritic steels at temperatures above 300 °C"

!The manufacturer shall be responsible for the fabrication and the installation, even if this work will be sub-contracted to other fabricators and/or installers."

Requirements on fabricators and installers of piping and supports

5.2.1 The fabricators and/or installers shall ensure the correct transport, handling, storage, fabrication, installation and testing of all piping components including supports."

5.2.2 The fabricators and installers shall have access to facilities which enable them to handle the piping components including supports correctly and to carry out the required tests.

5.2.4 All stages of fabrication and installation shall be supervised in such a way as to maintain the design integrity of the finished system.

Requirements for fabrication and installation

5.3.1 Prior to any operation, a check shall be made to ensure that the spools and components supplied are in accordance with the relevant documents (specifications, drawings, certificates etc.)

5.3.2 Prefabricated spools and components shall be protected during handling, transport, and storage

5.3.3 When joining spools or components, they shall not be strained nor deformed other than as may be required by the design Designer's installation instructions, if any, shall be observed

5.3.4 Any temporary supports or restraints used as an aid during transport, installation or testing shall be removed prior to commissioning

To prevent corrosion in stainless steel and non-ferrous materials, it is essential to implement appropriate measures against contamination In the event of contamination, it must be promptly and effectively removed, regardless of any final treatment applied.

NOTE Recommended methods for the prevention and removal of contamination on stainless steel are given in Annex A

5.3.6 Piping for fluids which are likely to cause condensation shall be installed with adequate slopes and traps.

Classification of piping

Fabricators and installers must utilize their own qualified supervisors and skilled personnel In cases where subcontractors are engaged, the fabricator and installer retain responsibility for ensuring their competence and adherence to this European Standard.

NOTE The task and responsibilities of a welding co-ordinator are described in EN ISO 1 4731 "

Effective coordination must be upheld between the design team and those involved in fabrication, installation, and testing This collaboration is essential to ensure that all processes align with the design specifications.

5.2.6 The fabricator and/or installer of the piping shall fulfil the requirements of EN ISO 3834-3."

The fulfillment of !NOTE 5.3.3 requires that the quality characteristics of the material remain intact during cold or hot forming processes, such as cutting, grinding, straightening, or bending Additionally, it is essential that the various components are joined in a manner that eliminates any stresses and deformations that could compromise the safety of the piping system.

!The piping systems shall be classified into different categories depending on the fluid carried, diameter and pressure These are given in EN 1 3480-1 "

Material grouping

!Material grouping is given in EN 1 3480-2."

Tolerances

!Tolerances shall comply with EN ISO 1 3920, class C and class G, except where other classes are specified in this European Standard or by design."

Angular tolerances for fabricated pipework shall be determined by the dimensional tolerance for the terminal points of the finished part

Alternative tolerances for pipework fabrication and installation must be specified, with all variations clearly identified in the documentation Additionally, the dimensional tolerances for fabricated spools should adhere to the guidelines outlined in Annex B.

General 1 0

Cutting and bevelling by machining shall be permitted for all materials

Flame cutting is applicable for material groups 1 and 2 for bevelling, provided that the desired bevel shapes and tolerances are met, and that the heat affected zone does not negatively impact the weld quality.

For material groups 3, 4 and 5, the heat affected zone shall be removed by machining or grinding.

For pressure components, it is essential to ensure material identification is maintained, either by preserving or transferring the marking required by the product standard, or by utilizing a unique code that is documented by the piping fabricator.

!Tolerances shall comply with EN ISO 1 3920, class C and class G, except where other classes are specified in this European Standard or by design."

!Flame cutting shall be permitted for material groups 1 , 2, 3, 4 and 5 only with preheating as specified for welding."

!Plasma cutting shall be permitted for all material groups given in this European Standard Plasma cutting shall be preceded by preheating, as specified for welding.

Other cutting and bevelling processes are permitted, provided their suitability is demonstrated."

!Stamping shall not introduce a notching effect, therefore low-stress stamping is recommended

If any method of marking other than hard-stamping, edging or engraving (vibrograph) is used, the fabricator shall ensure that confusion between different materials is not possible."

General 1 0

7.1 1 Fabricators of formed pressure parts shall have adequate procedures, equipment and tools for the forming and the subsequent heat treatment.

Pipes with internal coating such as glass, rubber or plastics shall not be formed unless it has been demonstrated that the forming process is not detrimental to the lining

NOTE There are two kinds of forming within the scope of this European Standard: cold forming and hot forming

The thickness after bending or forming shall be not less than that required by the design

Longitudinal welds should be located at the neutral zone The range of the neutral zone after bending is given in Figure 7.1 1 -1 " 9

Angular tolerances for fabricated pipework shall be determined by the dimensional tolerance for the terminal points of the finished part

Alternative tolerances for pipework fabrication and installation must be specified, with all cases clearly identified in the specification Additionally, dimensional tolerances for fabricated spools should adhere to the guidelines outlined in Annex B.

Cutting and bevelling by machining shall be permitted for all materials

Flame cutting is applicable for material groups 1 and 2 for bevelling, provided that the desired bevel shapes and tolerances are met, and that the heat affected zone does not negatively impact the weld quality.

For material groups 3, 4 and 5, the heat affected zone shall be removed by machining or grinding

For pressure components, it is essential to ensure material identification is maintained, either by preserving or transferring the mark required by the product standard, or by utilizing a unique code documented by the piping fabricator.

!Flame cutting shall be permitted for material groups 1 , 2, 3, 4 and 5 only with preheating as specified for welding."

!Plasma cutting shall be permitted for all material groups given in this European Standard Plasma cutting shall be preceded by preheating, as specified for welding.

Other cutting and bevelling processes are permitted, provided their suitability is demonstrated."

!Stamping shall not introduce a notching effect, therefore low-stress stamping is recommended

If any method of marking other than hard-stamping, edging or engraving (vibrograph) is used, the fabricator shall ensure that confusion between different materials is not possible."

7.1 1 Fabricators of formed pressure parts shall have adequate procedures, equipment and tools for the forming and the subsequent heat treatment

The procedure for bending shall be qualified according to EN 1 2952-5:2011 , Annex A, with regard to examination and range of qualification.

(a) optimal range for the longitudinal weld at bending

Figure 7.1 1 -1 — Optimal range for the longitudinal weld at bending

7.1 2 The forming and post-forming heat treatment of thermomechanical steels shall be given individual consideration Account shall be taken of the recommendations of the steelmakers

Pipes produced through thermomechanical processes like controlled rolling can be shaped using cold methods However, these materials may undergo significant alterations during the forming process, necessitating careful attention to restore their specified properties post-formation.

The percentage deformation for cold-formed cylinders and cone products made by rolling is calculated using specific formulas For cylinders and cones rolled from flat materials, refer to the relevant figures for guidance.

V = e (7.1 3-1 ) b) For cylinders and cones rolled from intermediate product (see Figures 7.1 3-1 b) and 7.1 3-1 c)):

The equation V e (7.1 3-2) defines key parameters in the manufacturing process, where eord represents the ordered thickness, eint denotes the thickness of the intermediate product, rmf indicates the average radius of the finished product, and r mi signifies the average radius of the intermediate product.

V d is the deformation as a percentage

If no intermediate quality heat treatment is conducted between forming steps, the total deformation equals the sum of the deformations from each step However, when intermediate quality heat treatment is applied, the deformation is only considered from the last treatment onward.

" a) Initial product b) Intermediate product c) Finished product

Figure 7.1 3-1 — Forming of cylinders and cones

7.1 4 Tools and equipment used for forming shall be maintained to ensure a smooth profile free from stress- raising defects, e.g scores

7.1 5 Heat treatment after forming shall be in accordance with the respective material standard

7.1 6 Welding on to formed areas shall not be performed until heat treatment is complete.

Heat treatment after cold forming 1 2

Flat products 1 2

Flat products shall be heat treated after cold forming as required in Table 7.2.1 -1

For special design reasons, for example cyclic loading or stress corrosion cracking, heat treatment in excess of that in Table 7.2.1 -1 may be specified after cold forming

Austenitic steels do not require heat treatment if they have a documented minimum elongation after fracture (A 5) of 30% or greater, and they can tolerate a maximum of 15% cold deformation.

A greater deformation may be accepted if the evidence is supplied that there is a minimum elongation after fracture (rupture) of 1 5 % after cold forming.

Evidence is considered provided if the acceptance certificate indicates that the elongation after fracture (rupture) A 5 is at least 30% This requirement applies only when there is no risk of stress corrosion cracking Additionally, for austenitic steels, the minimum value of elongation after fracture (rupture) A 5 must be less than the specified threshold.

30 %, evidence shall be supplied that there is a minimum elongation of 1 5 % after cold forming; c) Deformation shall not exceed 1 0 % if the working temperature is below -1 96 °C.

Table 7.2.1 -1 — Heat treatment after cold forming of flat products

Material groups according to CEN ISO/TR 1 5608

If heat treatment is not performed, qualification tests must be conducted to ensure that the material properties remain intact Heat treatment is necessary according to material standards when the minimum metal temperature falls below -10 °C Additionally, solution annealed, quenched, or stabilized materials do not require further heat treatment after cold forming.

Pipes .1 3

Pipes shall be heat treated after cold forming in accordance with Table 7.2.2-1

For special reasons, for example cyclic loading or stress corrosion, heat treatment may be specified after cold forming

Table 7.2.2-1 — Heat treatment after cold forming of pipes

Material groups according to CEN ISO/TR 1 5608

Mean bending radius of the pipe r m

Outside diameter of the pipe d o

Heat treatment is necessary for materials with a minimum metal temperature below -10 °C, as specified in the material standards If heat treatment is not performed, qualification tests must be conducted to ensure that the material properties remain unaffected However, this requirement does not apply to material groups 8.1 and 8.2.

Heat treatment after hot forming 1 4

Material groups 1 , 3, 4, 5 and 6 1 4

After hot forming processes like induction bending, it is essential to heat treat the components—through methods such as normalising, tempering, quenching, or annealing—according to the material specifications This ensures that the properties align with the required material standards Special attention must be given to materials intended for use in extreme temperatures, whether elevated or sub-zero, as well as under other specific conditions.

Hot forming of materials in groups 1, 3, and 5 with up to 2% Cr, when conducted within the specified temperature range, allows for the following: a) normalized steels do not require re-normalization; b) quenched and tempered steels only need tempering if they have been rapidly cooled by water or air from the forming temperature.

Pipes bent using the incremental induction heating method (induction bends) may undergo thermal treatment during bending by the application of water or air quenches

Non-alloy steels (C, C-Mn) produced through the induction bending process, followed by air or water quenching, can be effectively utilized in their as-bent state for applications that do not demand high impact resistance and ductility.

Such bends may be supplied without post-bending heat treatment provided that bend hardness does not exceed 285 HV

Heat treatments for high alloyed ferritic material should follow as soon after forming as practicable, to minimise the risk of hydrogen induced cracking.

The manufacturer must verify that the final product meets the necessary properties through the examination and testing of one or more sample bends These sample bends should be produced according to all relevant production parameters, which encompass chemical composition, forming temperature, forming rate (speed), coolant supply, and forming dimensions.

(e.g bend radius and r m / d o ) and post-forming heat treatment

Material groups 8.1 and 8.2 1 5

Austenitic steels that are rapidly cooled from above the solution annealing temperature using water or air during forming do not need post-forming heat treatment However, stabilised austenitic steels formed above this temperature require a post-forming stabilising treatment Conversely, stabilised austenitic steels formed within the stabilising temperature range do not require any further treatment.

Heat treatment shall be carried out in accordance with Table 7.3.2-1

Table 7.3.2-1 — Heat treatment of austenitic steels after hot forming

Material type Typical steel grades Conditions under which post-forming heat treatment may be waived Temperature range for heat treatment when stabilising a

Name Number Non-welded parts Welded parts Non-welded parts °C Welded parts °C °C

Stabilised steels non-Mo-alloyed X 6 CrNiTi 1 8-1 0

Forming started at 1 000 °C to 1 1 50 °C and finished at

> 750 °C (fastest possible Cooling) and stabilised fillers or non-stabilised fillers with

(X 4 NiCrMoCuNb 20-1 8) e 1 4505 ≥ 1 050 non stabilised steels low C-content/ non-Mo-alloyed

1 4439 ≥ 1 040 high C-content/ non Mo-alloyed X 4 CrNi 1 8-1 0

> 875 °C (quenching in/with water for wall thicknesses ≥ 6 mm)

Forming started at 1 000°C to 1 1 50 °C e and finished at

> 875°C (quenching in/with water for wall thicknesses

≥ 6 mm) and stabilised fillers or non-stabilised fillers with

≤ 0,06 % C not permitted not permitted ≥ 1 000 high C-content/

In Table 7.3.2-1, it is noted that stabilising or corresponding annealing is applicable for non-stabilised steels with a critical interval of approximately 30 minutes For materials with an equivalent diameter (e ord) of 6 mm or greater, cooling must be conducted through quenching in water or in an air flow (W SL) Conversely, for e ord less than 6 mm, cooling should occur in an air flow (L) A minimal critical interval of 5 minutes is required unless dictated by specific process conditions The starting temperature of 1,000 °C can be reduced if the part was previously in a quenched state before hot forming Additionally, stabilising is not allowed when stabilised fillers are utilized, and steels No 1.4406 and 1.4429 can be stabilised at lower temperatures while still achieving the same material characteristics.

Heat treatment after hot forming for material group 1 0

After hot forming, the parts shall be heat treated in accordance with the material specifications.

Heat treatment after hot forming for clad materials

If forming cannot be avoided, then the process of forming and heat treatment shall be demonstrated as giving specified properties.

Tolerances

Out-of-roundness of bends under internal pressure equal to, or greater than, the external

The out-of-roundness, u (in %), shall be calculated from:

= − (7.4.1 -1 ) where max do is the maximum outside diameter measured, in mm; min do is the minimum outside diameter measured at the same cross section as d o max , in mm

The out-of-roundness of the bend shall not exceed the limits given in Figure 7.4.1 -1

The ends of the bent pipes shall comply with the tolerances for the base pipe

Key do is the outside diameter rm is the mean bending radius u is the out-of-roundness

Figure 7.4.1 -1 — Acceptable out-of-roundness

Out-of-roundness of bends under external pressure and vacuum 1 8

Values for out-of-roundness shall conform to the values stated in the design.

Waves at bends

Waves at bends are acceptable as long as they comply with both of the following conditions: a)

01 m 0,03d h ≤ (7.4.3-1 ) where hm is the mean height of adjacent waves, calculated as follows:

04 03 m d022d d h = + − (7.4.3-2) where d 01 , d 02 , d 03 , d 04 are as shown in Figure 7.4.3-1 b)

≥ a (7.4.3-3) where a is the wave distance; h m is the mean height of adjacent waves, calculated as in Formula (7.4.3-1 )

NOTE For clarity, waves have been exaggerated

Start-up bulge of induction bends 1 9

The height of a start-up bulge or hump must not exceed 25% of the nominal wall thickness, and its base dimension should be at least eight times its height, ensuring a smooth transition into the adjacent surfaces.

The out-of-roundness tolerance specified in 7.4.1 shall also be applicable on a cross-section taken at the point of irregularity

4 h≤ e where e is the nominal wall thickness

Surface finish

The surface of the bend shall be such as to permit a visual examination

All bends must be devoid of surface defects, including cracks, indentations, laps, and scabs If imperfections are ground out, the wall thickness must not fall below the calculated minimum Additionally, areas that have been ground to eliminate these imperfections should be inspected using suitable surface crack detection methods to confirm the complete removal of defects.

Repairs by welding shall not be permitted

Fixing and alignment

Piping installation must adhere to the design specifications outlined in EN 1 3480-3 For specialized operations such as balancing and cold pull, specific instructions should be provided It is essential to verify that the piping maintains a continuous slope as per the design requirements.

During the assembly of piping sections, it is essential for the installer to utilize temporary supports to prevent unacceptable stress or deformation in the piping and connected equipment caused by the cantilever effect of unsupported weight distribution.

Temporary auxiliary supports should be used to replace the supporting effort of connected equipment.

Piping shall not be distorted for the purpose of alignment for joint assembly

Such distortion can introduce detrimental strains in the piping or connected equipment

Longitudinal welds shall be located so as to avoid openings or attachments wherever possible

Longitudinal welds in adjoining components shall be staggered by twice the nominal wall thickness, with a minimum distance of 20 mm

Supports shall be installed to ensure that the identification, load and travel scales are readily visible All threaded parts shall be fully engaged, and locking nuts tightened

The installer shall ensure that all clamping parts fit closely on the pipe

For pipes larger than DN 50, supports should be placed no more than one outside diameter from the designated position unless otherwise specified in the design Additionally, adjustments must be made to the support's attachment to the structure to ensure that the angulation of the support rods adheres to the specified limits.

During the installation and assembly of piping, variable spring hangers and constant load hangers must be blocked unless the design instructions specify otherwise If these supports are unblocked for specific operations like balancing or cold pull, they must be re-blocked before conducting hydrostatic pressure tests and chemical cleaning.

Temporary adjustment of the springs should be considered for operations such as hot chemical cleaning.

The installer must verify that the load settings of spring supports are configured according to design specifications If adjustments to the load are necessary, the installer should ensure that these modifications do not hinder or diminish the expected travel of the support.

Sliding supports and guide bearings must be positioned in the cold state to ensure that the sliding pad is properly supported during all anticipated movements as per the design specifications.

Before final assembly, the piping system shall be examined and any potential restrictions to the planned movements shall be removed

When cold pull is specified, it is essential to perform pulls against permanent anchors to maintain proper gaps and orientation during welding and heat treatment of the final joints After completing the cold pull, the installer must verify that the piping has assumed the intended cold positions If adjustments are needed for a variable spring and constant load hanger, such as using a turnbuckle and rod, the installer should ensure that adjacent supports can move freely as per the design requirements.

Expansion joints must be installed following the system analyst's specifications, including orientation and cold pull, as well as the supplier's installation instructions for the specific expansion joint.

After final assembly and the hydrostatic pressure test, the installer shall ensure that all temporary supports and blocking devices are removed.

Field run piping

Field run piping shall be made in accordance with the requirements given in EN 1 3480-3 regarding the span of supports, risks of vibration and the flexibility of the system

Field run piping shall be laid so that no clashes occur with other piping and structures during subsequent operation

The position of the piping during service should be taken into account.

Ease of access and replacement of components shall be ensured

Flanged or similar mechanical connections

Flange connections

Before assembly, the installer shall ensure that all flange faces are clean

Flanges shall be brought up flush and square, without forcing, so that the entire mating surfaces bear uniformly on the gasket, and then tightened up with uniform bolt tension

Flanges must be aligned to ensure that the bolt holes are evenly distributed on both sides of a line perpendicular to the pipe's plane Proper alignment of mating flanges is essential for the correct installation of bolts.

Flange bolts shall be tightened to the value specified for the joint design

Advice on training of personnel can be found in CEN/TS 1 591 -4

In accordance with European Standards, specific requirements must be adhered to: a) Nuts must be securely fastened onto bolts, ensuring that at least one full thread of the bolt is visible b) The minimum thread length for bolts and studs entering the threaded hole is determined by the material of the fasteners and their nominal diameter \(d\).

I e is d for steel and steel castings

(a) is the plane of pipe

Threaded connections

The sufficient number of threads shall be inserted into each fitting, and the fitting shall not bottom either on the end of the pipe or on the washout thread

NOTE Threaded connections include unions and threadolets

Suitable jointing compounds, sealing tapes etc may be used for all threaded joints with the exception of those required to be seal welded

Seal welding shall be performed by qualified welders to qualified welding procedures.

Couplings and compression fittings

Couplings and compression fittings must adhere to European Standards or receive approval from the piping manufacturer for their intended use They should be clearly marked with appropriate type information Additionally, all components of any coupling or compression fitting that does not meet European Standards must be sourced from the same manufacturer.

Tubes used with compression fittings shall meet the requirements specified by the fitting manufacturer Burrs and deformed areas shall be removed before assembly.

Protection of ends of piping components

To ensure the safety of piping components such as bevels, threaded ends, and flange faces during transport, storage, and assembly, appropriate protective measures like covering or coating should be implemented It is essential that any end protection applied by the fabricator is only removed right before the components are joined.

Welding personnel

9.1 2 Welding work shall be monitored by a welding co-ordinator

NOTE The task and responsibilities of a welding co-ordinator are described in EN ISO 1 4731

Welding procedure specifications

Verification of suitability

The suitability of the intended welding procedures shall be verified on the basis of a welding procedure qualification in accordance with Table 9.3.1 -1

Table 9.3.1 -1 — Qualification of welding procedures

II, III Welding procedures shall be qualified in accordance with EN ISO 1 561 4-1 :2004 or

EN ISO 1 561 3:2004 and approved by a responsible authority a

I Welding procedures for the pressure envelope shall be qualified in accordance with

EN ISO 1 561 4-1 :2004 or EN ISO 1 561 3:2004 as relevant unless the design specifications specify that EN ISO 1 561 1 :2003 or EN ISO 1 561 2:2004 is acceptable

Welding procedures for pressure envelope components must be qualified according to EN ISO 15614-1:2004, EN ISO 15614-1:2003, EN ISO 15614-2:2004, or EN ISO 15614-3:2004 In contrast, welding procedures for non-pressure retaining parts should adhere to the qualifications outlined in EN ISO 15614-0:2003.

Categories are defined in EN 1 3480-1 A responsible authority is an independent organization from the manufacturer, which may serve as a notified body or a recognized third-party organization within the jurisdiction of the European Union.

This European Standard does not invalidate prior welding procedure tests conducted under previous national standards or earlier versions of this standard If additional tests are required for technical equivalence, they should only be performed on a test piece made according to this European Standard.

Application

9.3.2.1 The application of the various processes shall depend on the material, size, intended use of the piping systems or their components and on the accessibility of the joints Nomenclature of processes and reference numbers for symbolic representation on drawings shall be in accordance with EN ISO 4063

For creep or fatigue applications surface imperfections shall meet the requirements of quality level B according to EN ISO 581 7

The suitability of the intended welding procedures shall be verified on the basis of a welding procedure qualification in accordance with Table 9.3.1 -1

Table 9.3.1 -1 — Qualification of welding procedures

II, III Welding procedures shall be qualified in accordance with EN ISO 1 561 4-1 :2004 or

EN ISO 1 561 3:2004 and approved by a responsible authority a

I Welding procedures for the pressure envelope shall be qualified in accordance with

EN ISO 1 561 4-1 :2004 or EN ISO 1 561 3:2004 as relevant unless the design specifications specify that EN ISO 1 561 1 :2003 or EN ISO 1 561 2:2004 is acceptable

Welding procedures for pressure envelope components must be qualified according to EN ISO 15614-1:2004, EN ISO 15614-1:2003, EN ISO 15614-2:2004, or EN ISO 15614-3:2004 In contrast, welding procedures for non-pressure retaining parts should comply with EN ISO 15614-0:2003.

Categories are defined in EN 13480-1 A responsible authority refers to a competent organization that operates independently from the manufacturer Within the European Union, this authority may be a notified body or a recognized third-party organization.

This European Standard does not invalidate prior welding procedure tests conducted under national standards or earlier versions of this Standard If additional tests are required for technical equivalence, they must be performed on a test piece made according to this European Standard.

9.3.2.1 The application of the various processes shall depend on the material, size, intended use of the piping systems or their components and on the accessibility of the joints Nomenclature of processes and reference numbers for symbolic representation on drawings shall be in accordance with EN ISO 4063

9.3.2.2 Oxy-acetylene welding processes shall only be used for: a) the material in accordance with CEN ISO/TR 1 5608, group 1 ; b) sizes DN 1 00 and smaller; c) wall thicknesses not exceeding 6 mm

The impact test must adhere to the relevant standards for qualifying welding procedures, and it is essential to comply with the impact test requirements specified in EN 13480-2.

For austenitic steels, when the minimum metal temperature T M of the piping is less than -1 05 °C the weld and heat-affected zones shall meet a minimum of 40 J when tested at -1 96 °C.

NOTE For practical reasons, the test temperature of -1 96 °C is standardized for all austenitic steels given in

EN 1 3480-2:201 2, Table B.2-11 of any design temperature below -1 05 °C.

The welding shall be performed in order to meet the requirements of quality level C according to

For creep or fatigue applications surface imperfections shall meet the requirements of quality level B according to EN ISO 581 7.

When welding high-alloy steel pipes from material groups 4, 6, 7, 8, and 10, it is essential to protect the inner surfaces from oxidation using appropriate shielding gas The type of shielding gas must be compatible with the specific pipe material.

Filler metals and auxiliary materials

The filler metals and auxiliary materials shall be suitable for the materials that are to be welded, the welding processes and the fabricating conditions

Electrodes, filler wires and rods shall be documented with at least a test report 2.2 according to EN 1 0204 The test report shall include the chemical analysis and mechanical properties

All welding consumables shall be stored and handled with care, and used in accordance with the conditions specified by the welding consumable manufacturer

Electrodes, filler wires and rods, and fluxes shall show no sign of damage or deterioration

NOTE Cracked or flaked coatings, rusting or dirty electrode wire are typical forms of damage or deterioration.

Climatic conditions

The welding area of the pipe shall be free of moisture (condensation, frost, ice)

In order to achieve this, it can be necessary to preheat the welding area.

Cleaning before and after welding

Welding surfaces, both internal and external, must be thoroughly cleaned to remove any paint, oil, rust, scale, or other contaminants that could negatively affect the quality of the weld or the base metal during the application of heat.

Coated components must have an adequate length of uncoated surface on both sides of the weld to ensure that the coating does not disrupt the welding process and to protect the integrity of the coating.

After welding, it is essential to clean the welded areas by removing any residues, slag, and spatter For specific guidance on treating austenitic stainless steel welds, please refer to Annex A.

The joint preparation shall be in accordance with the applicable WPS

NOTE Basic weld joint details are given in EN 1 708-1 and EN 1 708-3 Examples for joint preparation are given in EN ISO 9692-1 , EN ISO 9692-2 and EN ISO 9692-4

9.3.2.2 Oxy-acetylene welding processes shall only be used for: a) the material in accordance with CEN ISO/TR 1 5608, group 1 ; b) sizes DN 1 00 and smaller; c) wall thicknesses not exceeding 6 mm

9.3.2.3 Where gas-shielded welding processes are used, particularly on site where chimney effects may occur, the shield gas flow shall be protected from draughts and interruption by external influences

NOTE The dimensions of the root gap are the dimensions after tack welding

Piping and components shall be fixed in such a way that excessive stressing of the welds due to shrinkage during welding is avoided

When the ends of piping components do not align within the tolerances set by the welding procedure specification (WPS), adjustments must be made through machining, drifting, or, if impractical, by welding to build up the inside or outside diameter prior to edge preparation If welding is used for this purpose, the following conditions must be met: a) the thickness of the components at the joining ends must meet the minimum design thickness before welding; b) the welding process must adhere to an approved procedure; c) the properties of the weld metal at the design temperature must be equal to or superior to those of the parent metal; d) the length of the welded area must be at least 25 mm, and if ultrasonic examination of the butt weld is required, it must be long enough to allow for a complete inspection.

During arc welding, piping shall be earthed so that no welding currents flow through spring hangers, constant load hangers, shock arrestors (shock absorbers, snubbers), machines, valves, mechanical connections etc

There shall be no damage or degradation in the mechanics of these components (e.g ball bearings) due to high welding currents

The specified preheating temperature in the WPS must be maintained throughout the tacking and welding processes It is essential to monitor this temperature using appropriate measuring instruments or temperature indicating crayons to ensure compliance.

The Welding Procedure Specification (WPS) must outline the necessary preheating and inter-pass temperatures for welding These preheating temperatures should be established based on factors such as the chemical composition and thickness of the metal, the welding process employed, and the arc parameters involved.

NOTE General recommendations for preheating are contained in EN 1 01 1 series

When required, the prepared welding edges shall be protected to prevent damage during transport and assembly of the pipes Damaged welding edges shall be reworked before assembly

To ensure proper alignment and adhere to root gap specifications, the components to be welded must be firmly secured in place using mechanical methods or tack welding.

The joints between austenitic steels and ferritic steels shall be welded with suitable austenitic or nickel based filler metals

9.1 2.1 The material of the backing rings shall be in accordance with the requirements of the welding procedure

The backing ring should not cause the joint to be restrained whilst contracting.

9.1 2.2 Permanent backing rings shall not be used in category III

For category I and II backing rings may be used under the following conditions:

To ensure optimal performance, the gap between the ring and the bores of both pipes must be minimized, not exceeding 0.4 mm Additionally, the ends of the pipes should be machined to achieve proper roundness and fit.

 Particular attention should be paid to such factors as the joint gap, the root face, the misalignment, the thickness of the ring and the welding procedure;

 If the weld is subject to corrosion, erosion aerated fluids, fatigue or creep, the use of rings is not recommended

9.1 2.3 Fusible inserts shall be of material which is compatible with the parent metal, and shall be completely fused into the joint

The suitability shall be demonstrated by a welding procedure test and approval relevant to the application 9.1 3 Attachments

When post-weld heat treatment is required, welding of the pipe support directly onto the pressure retaining parts shall be made before post-weld heat treatment

Temporary attachments like rods and lugs must be welded to piping using a qualified welding procedure and compatible filler metal These fixings should be removed through cutting or grinding, ensuring that any temporary weld metal is also eliminated to maintain smooth surfaces It is crucial that this process does not compromise the wall thickness of the pipework below the minimum calculated standards Additionally, temporary fixings and weld metal must not be removed by hammering.

Arc strikes shall be avoided All accidental arc strikes shall be ground smooth and the area shall be inspected. 9.1 1 3 External welds

External welds on the pressure envelope (e.g fillet welds) shall show no evidence of burn-through

Oxide formation should be avoided on the rear side in the case of austenitic, corrosion-resistant steels."

All post-weld heat treatment (PWHT) shall be performed in accordance with a written procedure PWHT shall be applied in accordance with Table 9.1 4.1 -1 or Table 9.1 4.1 -2 on completion of welding

For steels not included in Table 9.1 4.1 -1 or Table 9.1 4.1 -2 the need for PWHT shall be given individual consideration

Post-weld heat treatment (PWHT) may be necessary for steels that are thinner than the thicknesses outlined in Tables 9.1 4.1 -1 and 9.1 4.1 -2, depending on service conditions such as stress corrosion cracking, low temperatures, or hydrogen embrittlement, as well as design requirements In such instances, it is essential to specify the appropriate temperature and holding time for the treatment.

If clad materials need PWHT, account shall be taken of the properties of the cladding materials

When additional welds or weld repairs have been made on a system after PWHT, a further treatment shall be carried out in accordance with Table 9.1 4.1 -1 or Table 9.1 4.1 -2, or a suitable alternative procedure

Precautions should be taken to prevent stresses during handling of piping assemblies prior to heat treatment

For PWHT, Pcrit values for material groups and materials are given in Table 9.1 4.1 -3

The heat treatment shall be performed taking into account the quality requirements given in

Welder's qualification for temporary welds shall be the same as that required for permanent welds

Pipe supports and permanent attachments must be made from the same materials as the connected pipe or from compatible materials to ensure structural integrity and compatibility.

Pipe support attachment welds to pipework shall be continuous unless the design specifies otherwise

Table 9.1 4.1 -1 — Post-weld heat treatment

Group a Material Post-weld heat treatment

1 2 Non-alloy steel with R eH ≤ 360 MPa (N/mm 2 )

1 3 Normalised fine grained steels with

360 MPa (N/mm 2 ) < R eH ≤ 460 MPa (N/mm 2 ) 550 to 600 b

360 MPa (N/mm 2 ) < R eH ≤ 690 MPa (N/mm 2 )

4 Low vanadium Cr-Mo-(Ni)-steel with

5.1 Cr-Mo-steel with 0,75 % ≤ Cr ≤ 1 ,5 % and free of vanadium (e.g 1 3CrMo4-5) < 1 5

5.2 Cr-Mo-steel with 1 ,5 % < Cr ≤ 3,5 % and free of vanadium (e.g 1 0CrMo9-1 0) 670 to 730 e

5.3 Cr-Mo-steel with 3,5 % < Cr ≤ 7,0 % and free of vanadium (e.g X1 6CrMo5-1 ) All 2w, minimum 60 700 to 750

5.4 Cr-Mo-steel with 7,0 % < Cr ≤ 1 0 % and free of vanadium (e.g X1 0CrMo9-1 )

6.1 High vanadium Cr-Mo-(Ni)-steel with

Materials not listed in the table require individual assessment Post-weld heat treatment (PWHT) is typically only necessary for specific cases such as stress corrosion, hydrogen embrittlement, and low temperatures For material 1.6Mo3, the recommended temperature range is between 550 °C and 620 °C Quenched and tempered steels should undergo PWHT at a temperature no more than 20 °C lower than the tempering temperature PWHT may be unnecessary for dimensions where d ≤ 114.3 mm and w ≤ 7.1 mm, provided the preheat temperature is 200 °C or higher and the service conditions do not mandate PWHT Additionally, intermediate cooling of the weld prior to PWHT is required to facilitate transformation into martensite.

Table 9.1 4.1 -2 — Post-weld heat treatment of material combinations

Material combination a Recommended welding consumables

Material Group Material Group Controlling

5.2 Non-alloy or Mo-alloy

1 2 Non-alloy or Mo-alloy < 35 d

1 3 Mo-alloy or Mn-Ni-alloy < 1 5

According to CEN ISO/TR 1 5608, materials not listed in the table require individual assessment Post-weld heat treatment (PWHT) may be unnecessary for dimensions where diameter \(d_a\) is less than or equal to 114.3 mm and width \(w\) is less than or equal to 7.1 mm, provided the preheat temperature is 200 °C or higher and PWHT is not mandated by service conditions For material 16Mo3, the recommended temperature range is between 550 °C and 620 °C PWHT is only required in specific situations, such as stress corrosion, hydrogen embrittlement, or low temperatures, for certain thicknesses Quenched and tempered steels should undergo PWHT at a temperature no more than 20 °C below the tempering temperature Additionally, intermediate cooling of the weld prior to PWHT is necessary to facilitate transformation into martensite.

Table 9.1 4.1 -3 — P crit values for Post weld heat treatment

5.1 1 3CrMoSi5-5 1 8,7 all others except 25CrMo4, 26CrMo4-2 1 8,5

6.4 X1 0CrMoVNb9-1 20,5 a Data for P crit are derived from EN 1 3445-4:2009.

Equipment for the heat treatment, monitoring and recording of the thermal cycle shall be suitable for the heat treatment in question

The temperature shall be measured on the surface of the weld unless otherwise specified

Where the component contains welded joints connecting parts which differ in thickness, the controlling thickness, w to be used in determining the requirements for PWHT times shall be:

 Butt welds (W1 0, W1 1 ) the thickest part of the welded joint;

 Fillet welds (W2) the specified thickness of the weld;

 Set-on branch (W3, W3.1 ) thickness of the branch at the joint;

 Set-through branch (W4) the greatest thickness of the weld joining the branch into the component;

 Repair by welding (W5) the thickness of the repair weld

NOTE See Figure 9.1 4.4-1 for examples of W1 0, W1 1 , W2, W3, W4 and W5

For components undergoing post-weld heat treatment (PWHT) that feature welds with varying individual controlling thicknesses, the overall PWHT should be based on the maximum individual controlling thickness.

For partial penetration welds, the controlling thickness shall be the welded thickness (W6)

NOTE See Figure 9.1 4.4-2 for examples of W3.1 and W6

Figure 9.1 4.4-1 — Typical examples of controlling thickness

Figure 9.1 4.4-2 — Weldolets 9.1 4.5 Rate of heating

The rate of heating or cooling above 300 °C shall not exceed 5 500/w °C/h with a maximum of 300 °C/h where w is the controlling thickness, in mm

Other rates of heating or cooling may be used if demonstrated acceptable by a welding procedure qualification test.

The manufacturer shall be able to demonstrate that the controlling thickness of the material has been heat treated in accordance with Tables 9.1 4.1 -1 and 9.1 4.1 -2

Pipes shall be supported during PWHT

It is recommended that ends should be closed.

The minimum number of measuring points for local heat treatment of pipes shall be taken according to

When local heat treatment of circumferential welds is applied by heating a heated band around the entire circumference, the heated band shall be at minimum:

D is the outer diameter of the pipe, in millimetres; t is the nominal thickness, in millimetres.

Insulation must be installed to maintain the weld and its heat-affected zones at the specified temperature, ensuring that the edge of the heated band reaches at least half of the peak temperature Additionally, insulation is necessary to prevent harmful thermal gradients outside the heated areas.

A minimum total insulated band width of 5⋅((2⋅D−4⋅t)⋅t) 0 , 5 is recommended for this purpose where

D is the outer diameter of the pipe, in millimetres, t is the nominal thickness, in millimetres

The welds or the sections thereof shall be identified by the welder’s symbol close to the weld

The weld identification may be replaced by corresponding details in the fabrication documents

Where deviations from the requirements are found during fabrication or installation, it shall be decided whether a repair or adjustment is necessary and possible

Edge protection

When required, the prepared welding edges shall be protected to prevent damage during transport and assembly of the pipes Damaged welding edges shall be reworked before assembly.

Assembly for welding